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Previous issue date: 2017-08-28 / Para atribuir sentido a uma seq??ncia de sons de uma m?sica, nosso c?rebro precisa encaixar e recombinar eventos ac?sticos em um fluxo continuo dentro de uma hierarquia sint?tica. Embora essas unidades de informa??o sejam ouvidas em seq??ncias com conex?es locais (uma ap?s a outra), assume-se que depend?ncias de longo prazo s?o estabelecidas contando com tra?os de mem?ria para sustentar a recursividade no tempo. Apesar disso ser um consenso te?rico e emp?rico, ainda n?o existe uma evid?ncia fisiol?gica clara da dimens?o temporal das rela??es sint?ticas na m?sica. N?s investigamos se h? atividade neural quantific?vel da exist?ncia de uma representa??o mental para regras fundamentais de sintaxe m?sical, como os acordes t?nica-dominante-t?nica. Para tal, utilizamos eletroencefalografia (EEG) comparamos a atividade el?trica do c?rebro em 24 indiv?duos (12 m?sicos, 12 n?o m?sicos) produzida por vers?es originais e harmonicamente modificadas de corais de J. S. Bach. Os corais eram compostos por duas frases: a primeira iniciada por um acorde de t?nica e chegando a um acorde dominante dois compassos depois (primeira frase), e a segunda concluiu em um acorde de t?nica tr?s compassos ap?s a dominante. As vers?es modificadas foram criadas elevando ou diminuindo as notas da primeira, mantendo assim a segunda frase intacta. Comparamos a resposta el?trica do c?rebro para o ?ltimo acorde em ambas as vers?es. / In order to make sense out of a sequence of sounds in music, our brain must meaningfully fit and recombine acoustic events into a hierarchic online stream. Although these information units are auditively delivered in sequences with local connections (one after the other), it is assumed that long-term dependencies are established counting on memory traces to sustain recursiveness in time. Despite theoretical and empirical consensus, there is yet no clear physiological evidence of the temporal dimension of syntactic relations in music. We investigated whether there is quantifiable neural activity suggesting the existence of a mental representation for fundamental music syntax rules like tonic-dominant-tonic chords. For such, we compared brain electric activity in 24 subjects (12 musicians, 12 non-musicians) aroused by original and harmonically modified versions of J.S. Bach chorales, using electroencephalography (EEG). Chorales were built by two phrases: initiated by a tonic and arriving in a dominant chord two bars away (first phrase), and concluded in a tonic chord three bars after the dominant (second phrase). Modified versions were created either by elevating or lowering the first, therefore keeping the second phrase intact. We compared the brain electric response for the last chord in both versions. Our data produced event related potentials (ERP) which suggest that the subjects? brain processed modified versions differently than originals. We observed an amplitude difference in the negativities peaking around 210 ms after the last chord onset. This finding replicates previous studies on harmonic disruptions processed in the same latency, but differs regarding brain source contributions: our data revealed a more posterior than anterior effect. Considering that last chords were the same acoustic event in both versions, we hypothesize that the amplitude differences plausibly indicate that the syntactic expectancy (long-term dependency between the tonic, dominant and tonic chord) may relate to brain mechanisms of processing non local connections, establishing a hierarchical storage of acoustic events in memory. We interpret that our parietal findings parallels with literature on mathematical sequence processing which suggest posterior brain regions to be engaged on complex calculation requiring the storage of numbers magnitude in memory for further computation. Our study overcame an obstacle not to date surpassed: observe and separate brain electric activity raised by long-term syntactic disruption in music from the overlap of local mismatch detection.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/24292 |
| Date | 28 August 2017 |
| Creators | Torrecuso, Renzo Alves Dantas |
| Contributors | 70638083460, Le?o, Emelie Katarina Svahn, 01771638605, Claessens, Peter Maurice Erna, 23190142840, Ribeiro, Sidarta Tollendal Gomes, Laplagne, Diego Andres |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM NEUROCI?NCIAS, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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